Trendelenburg control mechanism



1970 w. D. DREW 3,492,67

TRENDELENBURG CONTROL MECHANISM Filed Feb. 25, 1968 I 5 Sheets-Sheet 1fi/ezzz or z'f/z'am pfew Feb. 3 1970 wqb. DREW 3,492,679

TRENDELENBURG CONTROL MECHANISM Filed Feb. 25. 1968 3 Sheets-Sheet 2 2#ezz 2501" Feb. 3, 1970 w. o; DREW 3,492,679

TRENDELENBURG CONTROL-MECHANISM v Filed Feb. 25. 1968 I 3 Sheets-Sheet 5United States Patent O 3 492 679 TRENDELENBURG coNrRoL MECHANISM WilliamD. Drew, Batesville, Ind., assignor to Hill-Rom Company, Inc.,Batesville, Ind., a corporation of Indiana Filed Feb. 23, 1968, Ser. No.707,616 Int. Cl. A61g 7/00; A47e 22/00 US. Cl. -68 7 Claims ABSTRACT OFTHE DISCLOSURE CROSS REFERENCE This invention is an improvement of theTrendelenburg position limit control contained in the Hillenbrand et al.Patent 3,237,212 issued Mar. 1, 1966.

BACKGROUND OF THE INVENTION This invention relates to hospital beds,more particularly it relates to electrically driven hospital beds. Inthese beds, a limit position control stops the motor when the headsection of the spring frames of the bed reaches a horizontal position.In the treatment of patients it is often necessary to lower the headsection of the spring frame of the bed from horizontal into theTrendelenburg position. To do this it is necessary to alter the limitposition control to permit continued operation of the motor when thehorizontal position of the head section of the spring frame is reached.

DESCRIPTION OF THE PRIOR ART The Hillenbrand et a1. Patent 3,237,212discloses an electrically driven hospital bed having a lower framesupported upon the floor. An upper frame is mounted upon said lowerframe for movement longitudinally of said frames. The spring frame issupported on said upper frame. A cross tube pivotally mounted upon thehead section of the spring frame engages a levelizer mounted upon theupper frame when the head section is in horizontal position. The motorof the bed is controlled by a rod that is rotated from a neutralposition to start the motor. A cam carried upon the upper frame is movedinto engagement with a pin on said rod to rotate the rod back to itsneutral position to stop the motor when the head section reacheshorizontal position.

When the head section of the spring frame is to be placed inTrendelenburg position, the cross bar on the head section is rotated onits pivots into position inclined with respect to the head section andheld in this position against the tension of a spring which normallyholds it at right angles thereto. A lever on the upper frame is operatedto alter the limit position cam to permit the motor to operate beyondthe normal limit position. The motor is then started and the headsection thereby lowered until the limit cam stops it when the headsection reaches Trendelenburg position. To restore the bed to normalafter the head section is raised slightly, the spring pulls the crosstube back into position at right angles to the head section and thelever is restored to normal to return the limit position cam to normal.

SUMMARY OF THE INVENTION The present invention has for its principalobject the provision of an improved mechanism for controlling thelowering the head section of the spring frame of an electric motordriven hospital bed into Trendelenburg position, which mechanism returnsto normal automatically as the head section is returned to horizontalposition.

The machanism consists of a cross tube fixed upon the head section ofthe spring frame and depending therefrom at right angles thereto; alevelizer pivotally mounted upon the upper frame of the bed andmaintained in vertical position by the engagement of a crank arm on thelevelizer with a spool in a preset mechanism. The levelizer is movedinto position inclined to vertical by axial movement of the spool; a tierod connects the crank arm to the cam plate to alter the limit positionof the head section operating means. The mechanism thus preset remainspreset without any part of the mechanism being held manually in alteredposition and is restored to normal automatically by restoration of thehead section of the spring frame to horiztontal.

The invention will be understood best from the detailed description andclaims which follow reference being had to the accompanying drawings in'which a preferred embodiment of the invention is shown by way ofexample and on which:

FIGURE 1 is a fragmentary side elevational view of a hospital bedcontaining the mechanism of the invention;

FIGURE 2 is a fragmentary plan View showing the limit the position camplate of the bed;

FIGURE 3 is a plan view showing the levelizer and preset mechanism;

FIGURE 4 is a fragmentary side elevational cross sectional view alongthe line 4-4 of FIGURE 3' looking in the direction of the arrows, drawnto an enlarged scale and showing the mechanism in preset position; and

FIGURE 5 is an elevational view of the present spool in preset position.

Referring noW to the drawings in more detail, from FIGURE 1 it will beseen that the bed of the type to which the instant invention appliescontains a lower frame 10 upon which an upper frame 11 is mounted formovements longitudinally of the lower frame. Attached to the upper frameis a spring frame containing a seat section 12 to which a head section13 is pivotally attached.

Fixed upon the head section 13 is a cross tube 14 that extendsdownwardly from the frame of the head section at right angles thereto.Pivotally mounted upon the upper frame is a levelizer 15 which the crosstube 14 engages when the head section 13 of the spring frame is inhorizontal position.

As will be seen best in FIGURES 3 and 4, the levelizer is in the generalshape of an inverted U the vertical legs 16 of which are attached to across tube 17 in any preferred manner such as by welding. Rivets 18project through the side rails of the upper frame 11 and into the crosstube 17 to pivotally mount the levelizer upon the frame 11. The rivetsare secured in the cross tube by suitable means such as drive pins 19.

Journaled in the side rails of upper frame 11 with its axis parallel tothe axis of tube 17 is a preset rod 20 that is equipped with knobs 21located at its outer ends. Fixed upon the preset rod is a preset spool22 best seen in FIGURE 5. The spool consists of a central cylinder 23the diameter of which is but slightly larger than the diameter of therod 20. Rising from each end of the section 23 are conical cams 24.Located at each end of the spool 22 is a larger diameter cylindrical endsection each of which is separated from the cam 24 by a radial shoulder26. Surrounding the preset rod 20, and abutted against the side rails offrame 11 and a suitable collar suitably fixed upon the rod 20, aresprings 27.

Fixed upon the levelizer tube 17 and extending across the preset rod 20is a crank arm 30 which when the preset rod is in normal positionengages the small diameter cylinder 23 of the preset spool. With thecrank arm in this position, the levelizer is disposed vertically and isengaged by the cross tube 14, when the head section of the spring framereaches its horizontal position. Connected to the crank arm 30 is a tierod 31 the other end of which is connected to the limit plate 32 that isslidably mounted beneath the section 12 of the spring frame and has adepending cam 32. Attached to the end of the tie rod 31 that isprojected through an opening in the crank arm 30 is a spring 33, theother end of which is connected to a cross member 34 of the upper frame11.

As is fully explained in the above mentioned patent a control rod 35carries a pin 36 which is disposed horizontally when the control rod 35is in its neutral position. When it is desired to lower the head section13 of the spring frame and to simultaneously move the upper frame 11 tothe right, as seen in FIGURES 1 and 2, control rod 35 is rotated toposition the pin 36 at an upward angle with respect to horizontal asshown at 36. As the upper frame 11 moves to the right, the cam 32engages the pin and moves it from the inclined position 36' down intohorizontal position and thereby bring the head section 13 of the springframe to rest with the cross tube 14 engaging the levelizer 15.

When it is desired to move the head section of the spring frame intoTrendelenburg position the motor of the bed is operated to raise thehead section slightly so as to remove pressure on the levelizer 15 bymoving the cross tube 14 a short distance thereabove. The preset rod 20is then moved axially by pushing one of the knobs 21 inwardly towardsthe frame 11. It will be noted that the preset rod can be moved ineither direction and as shown in FIGURE it has been moved to the rightto move the preset spool 22 from the position in which it is shown indotted lines into position shown in full lines.

This movement of the preset spool, through the engagement of the crankarm 30 with the cam 24, raises the crank cam and thereby moves thelevelizer out of vertical position into position inclined with respectto vertical, as shown in FIGURE 4. This movement increases the tensionof spring 33 and the crank arm 30 is held against the end cylinder 25and the preset spool is held against the tension of the operated one ofits encircling springs 27 by the engagement of the crank arm with theradial shoulder 26. Upward movement of the crank arm 30 moves tie rod 31to the left as seen in FIGURE 2 thereby sliding the limit plate 32 so asto require greater movement of the frame 11 before the cam 32 engagesthe pin 36. The mechanism is thus preset to permit lowering the headsection 13 of the spring frame into Trendelenburg position and isretained in this preset position in the foregoing manner thus leavingthe attendants hand free to control the movement of the bed and to carefor the patient should special attention he required.

Downward movement of the head section 13 causes the cross tube 14 toslide down the edge of the vertical arm 16 of the levelizer 15. Thisraises the crank arm 30 which in turn further slides the limit plate 32so as to permit lowering the head section into Trendelenburg position.Downward movement of the head section can continue until cross tube 14engages crank arm 30, although this extreme position will seldom beused.

Elevation of the crank arm 30 by the rotation of the levelizer aroundits pivot disengages the crank arm from the radial shoulder 26 on thepreset spool and the spring 27 compressed by the longitudinal movementof the preset rod 20 restores that rod and spool to its normal positionin which the small diameter central cylinder 23 is aligned with thecrank arm 30.

When it is desired to restore the head section 13 of.

the spring frame to its normal horizontal position, control rod 35 isrotated in the opposite direction and the motor of the bed operated toraise the head section and simultaneously move the upper frame 11towards the head end of the bed. As the cross tube 14 moves upwardlyalong the levelizer, spring 33 pulls the levelizer back into itsvertical position and tie rod 31 restores cam 32 to its normal position.When the levelizer is in vertical position, crank arm 30 is reregisteredwith the small diameter cylinder 23 thus bringing the mechanism back toits normal position.

From the foregoing, it will be apparent that the preset controlmechanism of the present invention, when moved to a preset positionpreparatory to lowering the head section of the bed into Trendelenburgposition, retains itself in preset position leaving the hands of thenurse or attendant free to operate the bed and administer to the patientshould necessity arise. The mechanism is of simple construction andcapable of operating satisfactorily over a long period of time withlittle or no maintenance.

Having thus complied with the statutes and shown and described apreferred embodiment of my invention, I have done so by way of exampleonly as there are many adaptations and modifications which can be madeby one skilled in the art within the teachings of the invention. What Iconsider new and desire to have protected by Letters Patent is pointedout in the appended claims I claim:

1. In a motor driven hospital bed that has a spring frame carried uponan upper frame that is supported upon and movable with respect to alower frame as the head section of the spring frame is raised from andlowered into horizontal position, and in which a control rod isjournaled in the lower frame for rotation around its axis and carries apin disposed horizontally when the rod is in neutral position andinclined upwardly with respect to horizontal when the rod is in operatedposition, and in which a limit position cam slidably mounted upon saidupper frame engages said pin and lowers it from operated to neutralposition as the head section of the spring frame moves into horizontalposition, an improved mechanism for enabling the head section of thespring frame to be lowered from horizontal into Trendelenburg position,said mechanism comprising:

(a) levelizing means including a cross tube fixed upon the head sectionof the spring frame and disposed at right angles thereto; and alevelizer pivotally mounted on the upper frame and normally disposedvertically and in engagement with said cross tube to hold the headsection in horizontal position;

(b) preset means for altering said levelizing means preparatory tomoving the head section downwardly;

(c) and means operated by said preset means for sliding the limitposition cam to alter the point of engagement of the plate with said pinon the control rod.

2. Mechanism as specified in claim 1 in which the preset means includesa preset rod journaled in the upper frame with its axis parallel to thepivotal axis of the levelizer; a preset cam spool fixed upon said rod;and a crank arm fixed upon the levelizer and engaging said spool.

3. Mechanism as specified in claim 2 in which the spool includes acentral cylinder engaged by said crank arm to hold the levelizer invertical position, conical cams one at each end of said central cylinderfor raising said crank arm as the spool is moved axially; a largerdiameter cylinder at each end of the spool into engagement with whichthe crank arm is moved by axial movement of the spool; and a radialshoulder, adjacent the inner end of each of said end cylinders, engagedby the crank arm, holds the spool in preset position.

4. Mechanism as specified in claim 3 in which movement of said crank armfrom the central to the end cylinder of the spool rotates said levelizeron its pivots to register the cross tube with the edge of the levelizer,and

in which downward movement of the cross tube cams the levelizer into aposition more inclined from vertical and raises the crank arm oil ofsaid end cylinder and out of engagement with said shoulder therebyreleasing the spool.

5. Mechanism as specified in claim 4 in which spring means encirclingthe preset rod restores the spool to its normal position with thecentral cylinder aligned with said crank arm.

6. Mechanism as specified in claim 5 in which a tie rod connectedbetween the crank arm and cam plate slides the cam plate as the crankarm moves upwardly to require movement of the cam plate through thenormal limit position before engaging the control rod pin to move itfrom operated to neutral position.

7. Mechanism as specified in claim 6 in which a spring UNITED STATESPATENTS 3,231,904 2/1966 Shulkin 5-69 X 3,237,212 3/1966 Hillenbrand etal 568 3,398,411 8/1968 Douglass 569 X 3,402,408 9/1968 Hutt 568 CASMIRA. NUNBERG, Primary Examiner U.S. C1. X.R. 5-66

